Stability Coefficient

Formula for stability coefficient in interstory drift

θ = |\frac{P △_{0}}{F_{0} h_{s x}}| = \frac{P_{x} / h_{s x}}{V_{x} / △_{x e}}

θ	Elastic Stability Coefficient
P	Total point-in-time gravity load supported by the structure
△₀	Elastic lateral first-order story drift
F₀	Forces in a story
h_sx	Story height
P_x	Total unfactored vertical design load at and above level x
V_x/△_xe	Story stiffness at level x, ratio of seismic shear force (Vx) divided by the corresponding elastic story drift (△xe)

;